#region Apache License
//
// Licensed to the Apache Software Foundation (ASF) under one or more 
// contributor license agreements. See the NOTICE file distributed with
// this work for additional information regarding copyright ownership. 
// The ASF licenses this file to you under the Apache License, Version 2.0
// (the "License"); you may not use this file except in compliance with 
// the License. You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
#endregion

using System;
using System.IO;

using log4net.Core;

namespace log4net.Util
{
  /// <summary>
  /// <see cref="TextWriter"/> that does not leak exceptions
  /// </summary>
  /// <remarks>
  /// <para>
  /// <see cref="QuietTextWriter"/> does not throw exceptions when things go wrong. 
  /// Instead, it delegates error handling to its <see cref="IErrorHandler"/>.
  /// </para>
  /// </remarks>
  /// <author>Nicko Cadell</author>
  /// <author>Gert Driesen</author>
  public class QuietTextWriter : TextWriterAdapter
  {
    #region Public Instance Constructors

    /// <summary>
    /// Constructor
    /// </summary>
    /// <param name="writer">the writer to actually write to</param>
    /// <param name="errorHandler">the error handler to report error to</param>
    /// <remarks>
    /// <para>
    /// Create a new QuietTextWriter using a writer and error handler
    /// </para>
    /// </remarks>
    public QuietTextWriter(TextWriter writer, IErrorHandler errorHandler) : base(writer)
    {
      if (errorHandler == null)
      {
        throw new ArgumentNullException("errorHandler");
      }
      ErrorHandler = errorHandler;
    }

    #endregion Public Instance Constructors

    #region Public Instance Properties

    /// <summary>
    /// Gets or sets the error handler that all errors are passed to.
    /// </summary>
    /// <value>
    /// The error handler that all errors are passed to.
    /// </value>
    /// <remarks>
    /// <para>
    /// Gets or sets the error handler that all errors are passed to.
    /// </para>
    /// </remarks>
    public IErrorHandler ErrorHandler
    {
      get { return m_errorHandler; }
      set
      {
        if (value == null)
        {
          // This is a programming error on the part of the enclosing appender.
          throw new ArgumentNullException("value");
        }
        m_errorHandler = value;
      }
    }

    /// <summary>
    /// Gets a value indicating whether this writer is closed.
    /// </summary>
    /// <value>
    /// <c>true</c> if this writer is closed, otherwise <c>false</c>.
    /// </value>
    /// <remarks>
    /// <para>
    /// Gets a value indicating whether this writer is closed.
    /// </para>
    /// </remarks>
    public bool Closed
    {
      get { return m_closed; }
    }

    #endregion Public Instance Properties

    #region Override Implementation of TextWriter

    /// <summary>
    /// Writes a character to the underlying writer
    /// </summary>
    /// <param name="value">the char to write</param>
    /// <remarks>
    /// <para>
    /// Writes a character to the underlying writer
    /// </para>
    /// </remarks>
    public override void Write(char value)
    {
      try
      {
        base.Write(value);
      }
      catch (Exception e)
      {
        m_errorHandler.Error("Failed to write [" + value + "].", e, ErrorCode.WriteFailure);
      }
    }

    /// <summary>
    /// Writes a buffer to the underlying writer
    /// </summary>
    /// <param name="buffer">the buffer to write</param>
    /// <param name="index">the start index to write from</param>
    /// <param name="count">the number of characters to write</param>
    /// <remarks>
    /// <para>
    /// Writes a buffer to the underlying writer
    /// </para>
    /// </remarks>
    public override void Write(char[] buffer, int index, int count)
    {
      try
      {
        base.Write(buffer, index, count);
      }
      catch (Exception e)
      {
        m_errorHandler.Error("Failed to write buffer.", e, ErrorCode.WriteFailure);
      }
    }

    /// <summary>
    /// Writes a string to the output.
    /// </summary>
    /// <param name="value">The string data to write to the output.</param>
    /// <remarks>
    /// <para>
    /// Writes a string to the output.
    /// </para>
    /// </remarks>
    public override void Write(string value)
    {
      try
      {
        base.Write(value);
      }
      catch (Exception e)
      {
        m_errorHandler.Error("Failed to write [" + value + "].", e, ErrorCode.WriteFailure);
      }
    }

    /// <summary>
    /// Closes the underlying output writer.
    /// </summary>
    /// <remarks>
    /// <para>
    /// Closes the underlying output writer.
    /// </para>
    /// </remarks>
    public override void Close()
    {
      m_closed = true;
      base.Close();
    }

    #endregion Public Instance Methods

    #region Private Instance Fields

    /// <summary>
    /// The error handler instance to pass all errors to
    /// </summary>
    private IErrorHandler m_errorHandler;

    /// <summary>
    /// Flag to indicate if this writer is closed
    /// </summary>
    private bool m_closed = false;

    #endregion Private Instance Fields
  }
}
